Re: [PATCH v18 1/9] drm/xe: Rename XE_BO_FLAG_SCANOUT to XE_BO_FLAG_FORCE_WC

Rodrigo Vivi
2026-03-04T13:50:50Z

On Wed, Mar 04, 2026 at 01:03:06PM +0000, Tvrtko Ursulin wrote:
> Rename XE_BO_FLAG_SCANOUT to XE_BO_FLAG_FORCE_WC so that the usage of the
> flag can legitimately be expanded to more than just the actual frame-
> buffer objects.
>
> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
> Suggested-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
> ---
> drivers/gpu/drm/xe/display/intel_fb_bo.c | 6 +++---
> drivers/gpu/drm/xe/display/intel_fbdev_fb.c | 12 ++++++++----
> drivers/gpu/drm/xe/display/xe_dsb_buffer.c | 4 +++-
> drivers/gpu/drm/xe/display/xe_fb_pin.c | 2 +-
> drivers/gpu/drm/xe/display/xe_initial_plane.c | 2 +-
> drivers/gpu/drm/xe/xe_bo.c | 16 +++++++++++-----
> drivers/gpu/drm/xe/xe_bo.h | 2 +-
> 7 files changed, 28 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/gpu/drm/xe/display/intel_fb_bo.c b/drivers/gpu/drm/xe/display/intel_fb_bo.c
> index db8b1a27b4de..d2e72dc5abd9 100644
> --- a/drivers/gpu/drm/xe/display/intel_fb_bo.c
> +++ b/drivers/gpu/drm/xe/display/intel_fb_bo.c
> @@ -45,9 +45,9 @@ int intel_fb_bo_framebuffer_init(struct drm_gem_object *obj,
> if (ret)
> goto err;
>
> - if (!(bo->flags & XE_BO_FLAG_SCANOUT)) {
> + if (!(bo->flags & XE_BO_FLAG_FORCE_WC)) {
> /*
> - * XE_BO_FLAG_SCANOUT should ideally be set at creation, or is
> + * XE_BO_FLAG_FORCE_WC should ideally be set at creation, or is
> * automatically set when creating FB. We cannot change caching
> * mode when the bo is VM_BINDed, so we can only set
> * coherency with display when unbound.
> @@ -57,7 +57,7 @@ int intel_fb_bo_framebuffer_init(struct drm_gem_object *obj,
> ret = -EINVAL;
> goto err;
> }
> - bo->flags |= XE_BO_FLAG_SCANOUT;
> + bo->flags |= XE_BO_FLAG_FORCE_WC;
> }
> ttm_bo_unreserve(&bo->ttm);
> return 0;
> diff --git a/drivers/gpu/drm/xe/display/intel_fbdev_fb.c b/drivers/gpu/drm/xe/display/intel_fbdev_fb.c
> index 87af5646c938..d7030e4d814c 100644
> --- a/drivers/gpu/drm/xe/display/intel_fbdev_fb.c
> +++ b/drivers/gpu/drm/xe/display/intel_fbdev_fb.c
> @@ -56,9 +56,11 @@ struct drm_gem_object *intel_fbdev_fb_bo_create(struct drm_device *drm, int size
> if (intel_fbdev_fb_prefer_stolen(drm, size)) {
> obj = xe_bo_create_pin_map_novm(xe, xe_device_get_root_tile(xe),
> size,
> - ttm_bo_type_kernel, XE_BO_FLAG_SCANOUT |
> + ttm_bo_type_kernel,
> + XE_BO_FLAG_FORCE_WC |
> XE_BO_FLAG_STOLEN |
> - XE_BO_FLAG_GGTT, false);
> + XE_BO_FLAG_GGTT,
> + false);
> if (!IS_ERR(obj))
> drm_info(&xe->drm, "Allocated fbdev into stolen\n");
> else
> @@ -69,9 +71,11 @@ struct drm_gem_object *intel_fbdev_fb_bo_create(struct drm_device *drm, int size
>
> if (IS_ERR(obj)) {
> obj = xe_bo_create_pin_map_novm(xe, xe_device_get_root_tile(xe), size,
> - ttm_bo_type_kernel, XE_BO_FLAG_SCANOUT |
> + ttm_bo_type_kernel,
> + XE_BO_FLAG_FORCE_WC |
> XE_BO_FLAG_VRAM_IF_DGFX(xe_device_get_root_tile(xe)) |
> - XE_BO_FLAG_GGTT, false);
> + XE_BO_FLAG_GGTT,
> + false);
> }
>
> if (IS_ERR(obj)) {
> diff --git a/drivers/gpu/drm/xe/display/xe_dsb_buffer.c b/drivers/gpu/drm/xe/display/xe_dsb_buffer.c
> index 1c67a950c6ad..a7158c73a14c 100644
> --- a/drivers/gpu/drm/xe/display/xe_dsb_buffer.c
> +++ b/drivers/gpu/drm/xe/display/xe_dsb_buffer.c
> @@ -54,7 +54,9 @@ static struct intel_dsb_buffer *xe_dsb_buffer_create(struct drm_device *drm, siz
> PAGE_ALIGN(size),
> ttm_bo_type_kernel,
> XE_BO_FLAG_VRAM_IF_DGFX(xe_device_get_root_tile(xe)) |
> - XE_BO_FLAG_SCANOUT | XE_BO_FLAG_GGTT, false);
> + XE_BO_FLAG_FORCE_WC |
> + XE_BO_FLAG_GGTT,
> + false);
> if (IS_ERR(obj)) {
> ret = PTR_ERR(obj);
> goto err_pin_map;
> diff --git a/drivers/gpu/drm/xe/display/xe_fb_pin.c b/drivers/gpu/drm/xe/display/xe_fb_pin.c
> index dbbc61032b7f..d4a9eb550cae 100644
> --- a/drivers/gpu/drm/xe/display/xe_fb_pin.c
> +++ b/drivers/gpu/drm/xe/display/xe_fb_pin.c
> @@ -429,7 +429,7 @@ int intel_plane_pin_fb(struct intel_plane_state *new_plane_state,
> return 0;
>
> /* We reject creating !SCANOUT fb's, so this is weird.. */
> - drm_WARN_ON(bo->ttm.base.dev, !(bo->flags & XE_BO_FLAG_SCANOUT));
> + drm_WARN_ON(bo->ttm.base.dev, !(bo->flags & XE_BO_FLAG_FORCE_WC));
>
> vma = __xe_pin_fb_vma(intel_fb, &new_plane_state->view.gtt, alignment);
>
> diff --git a/drivers/gpu/drm/xe/display/xe_initial_plane.c b/drivers/gpu/drm/xe/display/xe_initial_plane.c
> index 65cc0b0c934b..8bcae552dddc 100644
> --- a/drivers/gpu/drm/xe/display/xe_initial_plane.c
> +++ b/drivers/gpu/drm/xe/display/xe_initial_plane.c
> @@ -48,7 +48,7 @@ initial_plane_bo(struct xe_device *xe,
> if (plane_config->size == 0)
> return NULL;
>
> - flags = XE_BO_FLAG_SCANOUT | XE_BO_FLAG_GGTT;
> + flags = XE_BO_FLAG_FORCE_WC | XE_BO_FLAG_GGTT;
>
> base = round_down(plane_config->base, page_size);
> if (IS_DGFX(xe)) {
> diff --git a/drivers/gpu/drm/xe/xe_bo.c b/drivers/gpu/drm/xe/xe_bo.c
> index 8ff193600443..fe560b0a980a 100644
> --- a/drivers/gpu/drm/xe/xe_bo.c
> +++ b/drivers/gpu/drm/xe/xe_bo.c
> @@ -515,7 +515,7 @@ static struct ttm_tt *xe_ttm_tt_create(struct ttm_buffer_object *ttm_bo,
> * For Xe_LPG and beyond up to NVL-P (excluding), PPGTT PTE
> * lookups are also non-coherent and require a CPU:WC mapping.
> */
> - if ((!bo->cpu_caching && bo->flags & XE_BO_FLAG_SCANOUT) ||
> + if ((!bo->cpu_caching && bo->flags & XE_BO_FLAG_FORCE_WC) ||
> (!xe->info.has_cached_pt && bo->flags & XE_BO_FLAG_PAGETABLE))
> caching = ttm_write_combined;
> }
> @@ -3196,8 +3196,14 @@ int xe_gem_create_ioctl(struct drm_device *dev, void *data,
> if (args->flags & DRM_XE_GEM_CREATE_FLAG_DEFER_BACKING)
> bo_flags |= XE_BO_FLAG_DEFER_BACKING;
>
> + /*
> + * Display scanout is always non-coherent with the CPU cache.
> + *
> + * For Xe_LPG and beyond up to NVL-P (excluding), PPGTT PTE
> + * lookups are also non-coherent and require a CPU:WC mapping.
> + */

I believe this comment should be now removed from the other place.
But it doesn't hurt if you decide to keep in both places.

Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

> if (args->flags & DRM_XE_GEM_CREATE_FLAG_SCANOUT)
> - bo_flags |= XE_BO_FLAG_SCANOUT;
> + bo_flags |= XE_BO_FLAG_FORCE_WC;
>
> if (args->flags & DRM_XE_GEM_CREATE_FLAG_NO_COMPRESSION) {
> if (XE_IOCTL_DBG(xe, GRAPHICS_VER(xe) < 20))
> @@ -3209,7 +3215,7 @@ int xe_gem_create_ioctl(struct drm_device *dev, void *data,
>
> /* CCS formats need physical placement at a 64K alignment in VRAM. */
> if ((bo_flags & XE_BO_FLAG_VRAM_MASK) &&
> - (bo_flags & XE_BO_FLAG_SCANOUT) &&
> + (args->flags & XE_BO_FLAG_FORCE_WC) &&
> !(xe->info.vram_flags & XE_VRAM_FLAGS_NEED64K) &&
> IS_ALIGNED(args->size, SZ_64K))
> bo_flags |= XE_BO_FLAG_NEEDS_64K;
> @@ -3229,7 +3235,7 @@ int xe_gem_create_ioctl(struct drm_device *dev, void *data,
> args->cpu_caching != DRM_XE_GEM_CPU_CACHING_WC))
> return -EINVAL;
>
> - if (XE_IOCTL_DBG(xe, bo_flags & XE_BO_FLAG_SCANOUT &&
> + if (XE_IOCTL_DBG(xe, bo_flags & XE_BO_FLAG_FORCE_WC &&
> args->cpu_caching == DRM_XE_GEM_CPU_CACHING_WB))
> return -EINVAL;
>
> @@ -3642,7 +3648,7 @@ int xe_bo_dumb_create(struct drm_file *file_priv,
> bo = xe_bo_create_user(xe, NULL, args->size,
> DRM_XE_GEM_CPU_CACHING_WC,
> XE_BO_FLAG_VRAM_IF_DGFX(xe_device_get_root_tile(xe)) |
> - XE_BO_FLAG_SCANOUT |
> + XE_BO_FLAG_FORCE_WC |
> XE_BO_FLAG_NEEDS_CPU_ACCESS, NULL);
> if (IS_ERR(bo))
> return PTR_ERR(bo);
> diff --git a/drivers/gpu/drm/xe/xe_bo.h b/drivers/gpu/drm/xe/xe_bo.h
> index c914ab719f20..af9a6669c872 100644
> --- a/drivers/gpu/drm/xe/xe_bo.h
> +++ b/drivers/gpu/drm/xe/xe_bo.h
> @@ -35,7 +35,7 @@
> #define XE_BO_FLAG_PINNED BIT(7)
> #define XE_BO_FLAG_NO_RESV_EVICT BIT(8)
> #define XE_BO_FLAG_DEFER_BACKING BIT(9)
> -#define XE_BO_FLAG_SCANOUT BIT(10)
> +#define XE_BO_FLAG_FORCE_WC BIT(10)
> #define XE_BO_FLAG_FIXED_PLACEMENT BIT(11)
> #define XE_BO_FLAG_PAGETABLE BIT(12)
> #define XE_BO_FLAG_NEEDS_CPU_ACCESS BIT(13)
> --
> 2.52.0
>